Method for operating a well jet device during cleaning of the downhole area of a formation and device for carrying out said method

ABSTRACT

The invention relates to pumping engineering, mainly to well pumping devices for extracting oil from wells. The inventive method consists in assembling from the bottom upward an input cone provided with a shank, a packer and a jet pump and in running said assembly with the aid of a tubing string into a well. Afterwards, a receiver transformer of physical fields is also run into said well, background measurements of temperature and other physical fields are carried out, a formation is drained and the work of the individual interlayer of a productive strata is evaluated. An ultrasonic action is performed on the productive strata. The hydrodynamic action being performed on the productive strata during said operation, the entire formation is exposed to the combined action of ultrasonic oscillations and a hydrodynamic effect. Afterwards, the unit for ultrasonic effect is pulled out from the well to the surface. The hydrodynamic and geophysical investigations of the well being carried out using the jet pump and replaceable functional inserts, the assembly and the jet pump are pulled out from the well to the surface and the well is prepared in order to be put into operation. The invention makes it possible to optimise the dimensions of various elements of the device, thereby increasing the operating reliability and performance of the well jet device during the treatment of the productive strata.

FIELD OF THE INVENTION

This invention relates to the field of pump engineering, primarily towell pump devices for extracting oil from wells.

PRIOR ART

Known in the art is a method of operating a well jet device, whichcomprises supply, via the tubing string, an active liquid medium to thenozzle of a jet device, wherein the said liquid medium entrains apassive medium and mixes with it while supplying the mixture of themedia out of a well to the surface (RU 2059891 C1).

Known from the same source is a well jet device, which comprises a jetpump being installed on the tubing string in a well, and a geophysicalinstrument being arranged in the tubing string below the said jet pump.

The known method of operation and the well jet device enable to pump outof a well various extracted media, e.g., oil, with the simultaneoustreatment of the extracted medium and the downhole area of a formation.

But, the said method does not provide for a possibility of selectivelyacting on the downhole area of a formation. Furthermore, the said devicedoes not provide for a possibility of installing various functionalinserts, what, in a number of cases, narrows the field of application ofthe said method of operation and the said device.

The closest to the present invention as to the technical essence and theachieved result in respect of the method is a method of operating a welljet device while treating a formation, the said method includesinstalling, in a well on the tubing string, a jet pump arranged in itscase wherein the latter has a through passage made in it, supplying, viathe tubing string to the nozzle of the said jet pump, a working medium,and creating owing to it a regulated pressure in the under-packer areawith the possibility of draining the formation and carrying out othermaintenance works (RU 2176336 C1).

The closest to the present invention as to the technical essence and theachieved result in respect of the device is a well jet device, knownfrom the same source, which comprise a packer, a tubing string and a jetpump, the case of the said pump comprising an active nozzle with amixing chamber, and a through passage being made with a mounting facefor installing a sealing assembly with an axial channel, the said devicebeing provided with an irradiator and receiver-transformer of physicalfields, which is arranged on the jet pump side for entry of the mediumpumped out of the well and is installed on the cable passed through theaxial channel of the sealing assembly, the passage for supplying theactive medium is connected to the tubing string above the replaceablefunctional insert, the input side of the jet pump's passage forsupplying the extracted medium is connected to the tubing string belowthe replaceable functional insert, and the output side of the jet pumpis connected to the tubing string hole clearance.

The known method of operation and the well jet device enable to treat aformation in a well below the level at which the jet pump is installed,including treatment of a producing formation with chemical agents, andto create a pressure differential above and below the functional insert.

However, the said method of operation and the said well jet device donot enable to utilize the capacity of the well jet device in full, whichis due to a limited number of operations for treating a formation,primarily with the use of chemically active liquid media, and to thelack of the possibility to exactly act on non-working or poorly workinglayers of a producing formation, as well as to non-optimal relationsbetween the dimensions of the components of the well jet device.

DISCLOSURE OF THE INVENTION

The objective to be achieved through this invention is to raise thereliability and productivity of the well jet device when treating aproducing formation owing to identifying non-working or poorly workinglayers of such a producing formation and exactly acting on the downholearea for restoring its permeability and removing mudding particles fromthe well, which foul the downhole area, as well as for optimizing thedimensions of various components of the device.

The stated objective is achieved in respect of the method due to thatthe method of operating the well jet device during ultrasonic cleaningof the downhole area of a formation consists in that an input cone witha shank, a packer and a jet pump, in the case of which a passage forsupplying an active medium, a passage for supplying the medium pumpedout of the well, and a stepped through passage with a mounting seatbetween the steps are made, are all installed bottom up, this assemblyis lowered on the tubing string into the well, the said input cone beingarranged not lower than the roof of the producing formation; after thisthe packer is released, and, then, a receiver-transformer of physicalfields is lowered in the well through the through passage, as made inthe case of the jet pump, on a logging cable or a wire together with asealing assembly, which is arranged on the logging cable or the wireabove the tip for connecting the receiver-transformer of physical fieldsand is installed onto the mounting seat in the through passage made inthe case of the jet pump, while ensuring the possibility of reciprocalmotion of the logging cable or the wire in the sealing assembly; duringthe process of lowering background measurements of temperature and otherphysical fields are conducted along the borehole from the input cone tothe well bottom; then the receiver-transformer of physical fields isarranged above the roof of the producing formation; the formation isdrained by supplying a liquid medium under pressure to the active nozzleof the jet pump, while several values of pressure drawdown on theformation are successively created and at each value well bottompressures, the composition and the physical parameters of the fluidcoming out of the producing formation as well as the well output areregistered; then, while operating the jet pump at a set value ofpressure drawdown on the formation, the receiver-transformer of physicalfields is moved along the well axis from the well bottom to the inputcone, during this operation the inflow profile and the parameters of theformation fluid, the well bottom pressure as well as the changes in thephysical fields in the downhole area of the formation are all registeredwith using the measurements for assessing the work of individual layersof the producing formation and the composition of the fluid coming outof them; then the supply of the liquid medium to the jet pump isstopped, the receiver-transformer of physical fields is removed from thewell together with the logging cable or the wire and the sealingassembly, then an instrument for ultrasonic action on the formation islowered into the well on the logging cable or the wire via the tubingstring, the said instrument comprising an irradiator of ultrasound,together with the sealing assembly movably arranged above it on thelogging cable; the latter is installed onto the mounting seat in thethrough passage, and the irradiator of ultrasound is installed oppositeto the producing formation; after this the producing formation is actedon by ultrasonic oscillations, first acting on its non-working layersand then on working layers while going successively from less permeableto more permeable layers and acting on each of them with not less thantwo ultrasonic frequencies; during the ultrasonic treatment of layers ofthe producing formation the latter is acted on hydrodynamically bysupplying a liquid medium to the active nozzle of the jet pump accordingto the following scheme: creation of stepwise drawdown on the formation,keeping of the said drawdown, stepwise restoration of the hydrostaticpressure of the liquid medium at the well bottom and keeping of thispressure, wherein the time of keeping the drawdown on the formation isset to be greater than the time of acting on the formation by thehydrostatic pressure of the liquid medium, and the number of cycles ofthe hydrodynamic action on each layer of the formation in combinationwith ultrasonic oscillations should not be less than 5; and afterfinishing acting on each layer of the formation with ultrasonicoscillations in combination with the hydrodynamic action a controlmeasurement of the well output is carried out while the jet pump isoperated, and after finishing acting on the whole formation withultrasonic oscillations in combination with the hydrodynamic action theinstrument for ultrasonic action on the formation is removed out of thewell to the surface, hydrodynamic and geophysical studies of the wellare conducted with the use of the jet pump and replaceable functionalinserts; then the assembly with the jet pump is taken to the surface,and the measures necessary for putting the well into exploitation arecarried out.

The stated objective is achieved in respect of the device due to thatthe well jet device comprises a receiver-transformer of physical fields,an instrument for ultrasonic action on the formation, replaceablefunctional inserts and, mounted bottom up on the tubing string, an inputcone with a shank, a packer with a central passage made therein and ajet pump, in the case of which the active nozzle and the mixing chamberare installed as well as the passage for supplying an active medium, apassage for supplying a medium pumped out of the well, and a steppedthrough passage with the mounting seat between the steps are made; inthe said stepped through passage alternatively installed are the sealingassembly, which is arranged movably on the logging cable or the wireabove the tip for connecting the receiver-transformer of physical fieldsor the instrument for ultrasonic action on the formation, andreplaceable functional inserts, i.e., a depression insert and an insertfor recording curves reflecting restoration of formation pressure in theunder-packer area of the well with a sampler and an autonomousinstrument; the said instrument for ultrasonic action on the formationcomprises an irradiator of ultrasound, which is made with thepossibility of irradiating ultrasonic oscillations at not less than 2frequencies, and a pressure gauge; the diameter D₂ of the steppedthrough passage in the case of the jet pump below the mounting seat isat least 1 mm greater than the diameter D₁ of the instrument forultrasonic action on the formation, and the diameter D₃ of the centralpassage in the packer is not less than the diameter D₂ of the steppedthrough passage in the case of the jet pump below the mounting seat.

An analysis of the operation of the well jet device has shown that thereliability and the productivity of the device may be increased byoptimizing the succession of the actions performed during cleaning ofthe near-borehole area of the formation in wells, in particular duringperforming works with treatment of the formation ultrasonically as wellas in the result of making various components of the device understrictly defined dimensions.

It has been identified that the above-said succession of actions enablesto operate the well jet device in combination with an instrument forultrasonic treatment of a producing formation most efficiently whilecarrying out works on intensifying the oil inflow from a producingformation due to increasing the permeability of non-working and poorlyworking layers of the producing formation. By studying the formationboth before and after ultrasonic treatment it is possible to initiallyassess the technical condition of the well, the properties of the fluidextracted from the well, the condition of the downhole area of theproducing formation, to identify non-working and poorly workingproducing layers, and to select the mode of treating the producingformation with ultrasound. After ultrasound treatment in combinationwith hydrodynamic action on the formation it becomes possible to assessthe quality of the conducted treatment of the downhole area of theproducing formation, and to select the mode of exploitation of the well.The alternating hydrodynamic action on the formation in combination withultrasonic oscillations action on the formation enables to increase theradius of treatment of the downhole area of the formation. At a createddrawdown the jet pump timely removes mudding particles from theproducing formation, which foul the latter; the said mudding particlesare rapidly transferred to the surface along the hole clearance aroundthe tubing string. The use of a receiver-transformer of physical fieldsand functional inserts, including, in particular, a sampler and a numberof autonomous instruments, which may be installed under the saidfunctional inserts, enables to study the medium coming out of the well.At the same time, it becomes possible to control visually the amount ofdrawdown and obtain information on the value of the current hydrostaticpressure from the above-said autonomous instruments and the instrumentsinstalled on the logging cable. Furthermore, when exerting ultrasonicaction on the formation due to changing the frequency of ultrasonicoscillations in combination with the regulated, above-described steppedalternating mode of pumping out by changing the pressure of the liquidworking medium supplied to the nozzle of the jet pump it has beenpossible to select such mode of operation, which not only restores thepermeability of non-producing layers, but also increases thepermeability and, consequently, the inflow of the extracted medium(fluid) from the producing layers of the formation. It has beenidentified that of significance for efficient action on the formationare the stepwise transition from a drawdown onto the formation torestoration of the hydrostatic pressure, which operation is repeated incycles, and exceeding of the time of maintaining the drawdown onto theformation in comparison to the time of exerting hydrostatic pressure ofthe liquid medium column, as exists in the well, on the formation. Ithas been also identified that the number of the said cycles ofhydrodynamic action on each of the layers should not be less than 5 inorder to clean the downhole area of the formation with good quality. Inthe course of carrying out the works on cleaning the downhole area ofthe formation it becomes possible to move the receiver-transformer ofphysical fields and the instrument for ultrasonic action on theformation along the well, and, moreover, it becomes possible to studythe formation and to treat it both at the operating jet pump and when itis stopped, which enables to carry out efficient measures forintensifying the well output with ultrasonic treatment of the producingformation, while carrying out the comprehensive study and testing of thewell in different modes. In the result, it has become possible to lower1.5–2 times the lower limit of the formation permeability, to destructthe mud fill area in the non-working layers of the producing formation,and, as a consequence, to accelerate 1.2–1.6 times the works onimproving the well productivity; and, moreover, the inflow profilebecomes significantly smoother due to the complete coverage of theformation by acting over its thickness in the course of treating theformation with ultrasound. It is necessary to note that the successionof the actions, as described in the invention, enables to permanentlymonitor the course of the works on intensifying the inflow of the mediumextracted from the producing formation. In particular, the obtainedinflow profiles and the curves reflecting the restoration of theformation pressure enable to get an objective view of the condition ofthe downhole area of the producing formation, depending on the performedworks on increasing its permeability.

Furthermore, in order to prevent the instruments, which are loweredalong the tubing string, in particular, an instrument for ultrasonicaction on the formation, from sticking and to ensure the uninterruptedoperation of the well jet device the diameter D₂ of the stepped throughpassage in the case of the jet pump below the mounting seat is at least1.0 mm greater than the diameter D₁ of the instrument for ultrasonicaction, and the diameter D₃ of the central passage in the packer is atleast 1.0 mm greater than the diameter D₂ of the stepped through passagein the case of the jet pump below the mounting seat. It has beenidentified that making the instrument for ultrasonic action on theformation with the outer diameter differing lesser than by 1 mm from thediameter of the stepped through passage below the mounting seat does notprevent it from sticking, since in the course of the device operationmudding particles may enter the gap between the instrument forultrasonic action and the wall of the stepped through passage. At thesame time, the said gap should be such that it may ensure flowing alongit the medium extracted out of the well in the course of moving theinstrument for ultrasonic action on the formation along the steppedthrough passage.

Thus, the set objective has been achieved—to raise the reliability andthe productivity of the well jet device while treating the producingformation—owing to identifying non-working and poorly working layers ofthe producing formation and exactly acting on the downhole area with therestoration of its permeability and removal of mudding particles, whichfoul the downhole area, our of the well, as well as owing to theoptimization of the dimensions of various components of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a longitudinal section of the well jet device intendedfor implementing the described method of operation where the well jetdevice comprises a sealing assembly and a receiver-transformer ofphysical fields.

FIG. 2 is a longitudinal section of the device together with a sealingassembly and an instrument for ultrasonic action on a formation.

FIG. 3 is a longitudinal section of the device together with thefunctional insert for recording curves reflecting the restoration offoundation pressure in the under-packer area, where a sampler and anautonomous instrument are installed under the functional insert.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The well jet device comprises, mounted bottom up on the tubing string 1,the input cone 2 with the shank 3, the packer 4 with the central passage5 made therein and the jet pump 6, in the case 7 of which the activenozzle 8 and the mixing chamber 9 are coaxially installed as well as thepassage 10 for supplying an active medium, the passage 11 for supplyinga medium pumped out of the well and the stepped through passage 12 withthe mounting seat 13 between the steps are made, the possibility beingprovided for installing the sealing assembly 14, which is arrangedmovably on the logging cable or the wire 15 above the tip 16 forconnecting the receiver-transformer of physical fields 17, theinstrument 18 for ultrasonic action on the formation, and replaceablefunctional inserts, i.e., a depression insert and an insert forrecording curves reflecting restoration of formation pressure in theunder-packer area 19 of the well with the sampler 20 and the autonomousinstrument 21 in the said stepped through passage. The instrument 18 forultrasonic action on the formation comprises an irradiator ofultrasound, which is made with the possibility of irradiating ultrasonicoscillations at not less than 2 frequencies, and a pressure gauge. Thediameter D₂ of the stepped through passage 12 in the case 7 of the jetpump 6 below the mounting seat 13 is at least 1 mm greater than thediameter D₁ of the instrument 18 for ultrasonic action on the formation.The diameter D₃ of the central passage 5 in the packer 4 is less thanthe diameter D₂ of the stepped through passage 12 in the case 7 of thejet pump 6 below the mounting seat 13. The output of the jet pump 6 isconnected to the borehole clearance of the well (the tubing string 1),the nozzle 8 of the jet pump 6 is connected, via the passage 10 forsupplying the active medium, to the inner cavity of the tubing string 1above the sealing assembly 14, and the passage 11 for supplying themedium pumped out of the well is connected to the inner cavity of thetubing string 1 below the sealing assembly 14. The functional insertsare made in their upper part with the tool 22 for their installing intoand extracting from the well.

The method of operating the well jet device during ultrasonic cleaningof the downhole area of a formation consists in that the input cone 2with the shank 3, the packer 5 with the central passage 5 and the jetpump 6, in the case 7 of which the passage 10 for supplying the activemedium, the passage 11 for supplying the medium pumped out of the well,and the stepped through passage 12 with the mounting seat 13 between thesteps, are all installed bottom up. This assembly is lowered on thetubing string 1 into the well, the input cone 2 being arranged not lowerthan the roof 23 of the producing formation. The packer 4 is released,and, then, the receiver-transformer of physical fields 17 is lowered inthe well through the through passage 12, as made in the case 7 of thejet pump 6, on the logging cable or the wire 15 together with thesealing assembly 14, which is arranged on the logging cable or the wire15 above the tip 16 for connecting the receiver-transformer of physicalfields 17. The sealing assembly 14 is installed onto the mounting seat13 in the through passage 12 made in the case 7 of the jet pump 6, whileensuring the possibility of reciprocal motion of the logging cable orthe wire 15 in the sealing assembly 14. During the process of loweringbackground measurements of temperature and other physical fields areconducted along the borehole from the input cone to the well bottom.Then the receiver-transformer of physical fields 17 is arranged abovethe roof of the producing formation, and the formation 23 is drained bysupplying a liquid medium under pressure to the active nozzle 8 of thejet pump 6, while several values of pressure drawdown on the formationare successively created and at each value well bottom pressures, thecomposition and the physical parameters of the fluid coming out of theproducing formation 23 as well as the well output are registered. Then,while operating the jet pump 6 at a set value of pressure drawdown onthe formation 23, the receiver-transformer of physical fields 17 ismoved along the well axis from the well bottom to the input cone 2, andthe inflow profile and the parameters of the formation fluid, the wellbottom pressure as well as the changes in the physical fields in thedownhole area of the formation 23 are all registered with using themeasurements for assessing the work of individual layers of theproducing formation 23 and the composition of the fluid coming out ofthem. Then the supply of the liquid medium to the jet pump 6 is stopped,the receiver-transformer of physical fields 17 is removed from the welltogether with the logging cable or the wire 15 and the sealing assembly14. Then an instrument for ultrasonic action on the formation 23 islowered into the well on the logging cable or the wire 15 via the tubingstring 1, the said instrument comprises an irradiator of ultrasound,together with the sealing assembly 14 movably arranged above it on thelogging cable or the wire 15. The latter is installed onto the mountingseat 13 in the through passage 12, and the irradiator of ultrasound isinstalled opposite to the producing formation 23. After this theproducing formation 23 is acted on by ultrasonic oscillations, firstacting on its non-working layers and then on working layers while goingsuccessively from less permeable to more permeable layers and acting oneach of them with not less than two ultrasonic frequencies. During theultrasonic treatment of layers of the producing formation 23 the latteris acted on hydrodynamically by supplying a liquid medium to the activenozzle 8 of the jet pump 6 according to the following scheme: creationof stepwise drawdown on the formation 23, keeping of the said drawdown,stepwise restoration of the hydrostatic pressure of the liquid medium atthe well bottom and keeping of this pressure, wherein the time ofkeeping the drawdown on the formation 23 is set to be greater than thetime of acting on the formation 23 by the hydrodynamic pressure of theliquid medium, and the number of cycles of the hydrodynamic action oneach layer of the formation 23 in combination with ultrasonicoscillations should not be less than 5; and after finishing acting oneach layer of the formation 23 with ultrasonic oscillations incombination with the hydrodynamic action a control measurement of thewell output is carried out while the jet pump 6 is operated. Afterfinishing acting on the whole formation 23 with ultrasonic oscillationsin combination with the hydrodynamic action the instrument 18 forultrasonic action on the formation is removed out of the well to thesurface, hydrodynamic and geophysical studies of the well are conductedwith the use of the jet pump 6 and replaceable functional inserts; thenthe assembly with the jet pump 6 is taken to the surface, and themeasures necessary for putting the well into exploitation are carriedout.

INDUSTRIAL APPLICABILITY

This invention may be applied in the oil and gas producing industry andin the mining industry when developing wells after drilling, whileconducting underground repair or restoration works on them for thepurpose of intensifying inflow in oil and gas wells.

1. The method of operating the well jet device during ultrasoniccleaning of the downhole area of a formation, comprising installingbottom up an assembly of an input cone with a shank, a packer and a jetpump, having a case with a passage for supplying an active medium, apassage for supplying the medium pumped out of the well, and a steppedthrough passage with a mounting seat between steps of the steppedthrough passage, lowering said assembly on a tubing string into thewell, said input cone being arranged not lower than a roof of aproducing formation; after said lowering step, releasing the packer,and, then, lowering a receiver-transformer of physical fields in thewell through the through passage, as made in the case of the jet pump,on a logging cable or a wire together with a sealing assembly, which isarranged on the logging cable or the wire above the tip for connectingthe receiver-transformer of physical fields and is installed onto themounting seat in the through passage made in the case of the jet pump,while ensuring the possibility of reciprocal motion of the logging cableor the wire in the sealing assembly; during the process of loweringconducting background measurements of temperature and other physicalfields along the borehole from the input cone to the well bottom; thenarranging the receiver-transformer of physical fields above the roof ofthe producing formation; draining the formation by supplying a liquidmedium under pressure to the active nozzle of the jet pump, whileseveral values of pressure drawdown on the formation are successivelycreated and at each value well bottom pressures, registering thecomposition and the physical parameters of the fluid coming out of theproducing formation as well as the well output; then, while operatingthe jet pump at a set value of pressure drawdown on the formation,moving the receiver-transformer of physical fields along the well axisfrom the well bottom to the input cone, during this operationregistering the inflow profile and the parameters of the formationfluid, the well bottom pressure as well as the changes in the physicalfields in the downhole area of the formation with using the measurementsfor assessing the work of individual layers of the producing formationand the composition of the fluid coming out of them; then stopping thesupply of the liquid medium to the jet pump, removing thereceiver-transformer of physical fields from the well together with thelogging cable or the wire and the sealing assembly, then lowering aninstrument for ultrasonic action on the formation into the well on thelogging cable or the wire via the tubing string, the said instrumentcomprising an irradiator of ultrasound, together with the sealingassembly movably arranged above it on the logging cable; installing thelatter onto the mounting seat in the through passage, and installing theirradiator of ultrasound opposite to the producing formation; after thisacting on the producing formation on by ultrasonic oscillations, firstacting on its non-working layers and then on working layers while goingsuccessively from less permeable to more permeable layers and acting oneach of them with not less than two ultrasonic frequencies; during theultrasonic treatment of layers of the producing formation acting on thelatter hydrodynamically by supplying a liquid medium to the activenozzle of the jet pump according to the following scheme: creatingstepwise drawdown on the formation, keeping of the said drawdown,stepwise restoring of the hydrostatic pressure of the liquid medium atthe well bottom and keeping of this pressure, wherein the time ofkeeping the drawdown on the formation is set to be greater than the timeof acting on the formation by the hydrostatic pressure of the liquidmedium, and the number of cycles of the hydrodynamic action on eachlayer of the formation in combination with ultrasonic oscillationsshould not be less than 5; and after finishing acting on each layer ofthe formation with ultrasonic oscillations in combination with thehydrodynamic action carrying out a control measurement of the welloutput while operating the jet pump, and after finishing acting on thewhole formation with ultrasonic oscillations in combination with thehydrodynamic action removing the instrument for ultrasonic action on theformation out of the well to the surface, hydrodynamic and geophysicalstudies of the well are conducted with the use of the jet pump andreplaceable functional inserts; then taking the assembly with the jetpump to the surface, and carrying out the measures necessary for puttingthe well into exploitation.